The Evolution of Living The Evolution of Living ThingsThings

Chapter 8.1 Change Over TimeChapter 8.1 Change Over Time

Differences among organismsDifferences among organisms

• Adaptation a hereditary characteristic that helps an organism to survive and reproduce in its environment

• Can include structures for behavior, finding food, protection, moving from place to place

• Species living things that share the same characteristics and adaptations

• Requirements can mate with one another to produce fertile offspring

• Example Red-eyed tree frog

Change over time

• Species today range from bacteria that lack cell nuclei to multi-cellular fungi (plants and animals)

• Earth age 4.6 billion years old

• Fossil evidence shows that living things have changed over time

• Process of evolution newer species have descended from older species

EvolutionEvolution

• The theory that populations accumulate changes over time

• Because of evolution scientist believe that all living things from daisies to crocodiles to humans share a common ancestor

Evidence of evolutionEvidence of evolution

• Fossil record solidified remains or imprints of once living organisms

• Fossils formed usually a dead organism is covered by a layer of sediment*minerals in the sediment may seep into the organism, gradually replacing the organism with stone*organism may not rot completely and form a hole in the rock called mold

» sedimentary layers

Trilobite an ancient aquatic animal related to the crab Seed fern leaf,

300 million years old

Reading the fossil recordReading the fossil record

• Fossil record a historical sequence of lifeshows the order in which evolutionary changes have occurredshows how environmental conditions on earth may have changed

• Time sequencing the deeper in the earth’s crust the less they look like present day organismsthe upper layers of the earths crust tend to

resemble present day creatures

Gaps in the fossil recordGaps in the fossil record

• For a fossil to form specific conditions must be present*skeleton must be buried in sediment that is very fine*oxygen O2 must not be present (it promotes decay)

» Conditions to create fossils are very rare, and sometimes fossils are difficult to find

Vestigial structuresVestigial structures

• Vestigial structure remnant of a once useful structure• Example appendix

See page pg. 180-181

Evidence of evolutionEvidence of evolution

• Evidence of evolution comparison of different organisms

• Skeletal structuressimilarities indicate that

animals are all related by a common ancestor»Evolutionary process modified these bones over millions of years to perform specialized functions

• DNA all have the same genetic DNA- no other genetic molecule has been found

»The more closely related the more similar the DNA is• Embryonic Structures

vertebrate embryos look very similar

»Changes in the process of embryo development produce different animals

Skeletal StructuresSkeletal Structures

• .Human arm

Cat leg

Dolphin flipper

Bat wing

The most similar bones are shown in the same color

DNA from different speciesDNA from different species

• .

Embryonic structuresEmbryonic structures

• .

The Evolution of Living The Evolution of Living ThingsThings

Chapter 8.2 How does evolution happen?Chapter 8.2 How does evolution happen?

How does evolution happenHow does evolution happen

• 1800s scientists realized earth is older than anyone had previously thought

• Evidence shows gradual processes had shaped the Earth’s surface over millions of years

Charles DarwinCharles Darwin

• 1831 graduated from college with degree in thoelogyfather wanted him to be a doctor but Darwin was

interested in natural scienceHMS BeagleDarwin took a 5 year voyage around the world serving

as a naturalistObservations Darwin made observations on this voyage that later

became the foundation for the theory of evolution by natural science

Darwin’s adventure Darwin’s adventure

• Collections thousands of plant and animal samplestook detailed notes

• Galapagos islands observed that animals and plants were similar but not identical to plants and animals in

nearby South America• Finches different than finches in South America

(Ecuador) and from each other (mainly the shape of their beak, and the food they ate)

• Theory finches that survived may have adapted to various ways of living on the Galapagos Islands

•

Darwin learned from farmers and Darwin learned from farmers and animal and plant breedersanimal and plant breeders

• Selective breeding humans choose the trait they want passed along to the next generation

• Farmers chose certain traits for farm animals• Breeders chose traits that shaped the breeds we see

today

Darwin learned from Darwin learned from geologistsgeologists

• Charles Lyell wrote “Principles of Geology” which said the Earth had been formed by natural processes over a long period of time

• Thomas Malthus wrote “Essay on the Principle of Population” which states that human populations have the potential to reproduce uncontrollably, beyond the available food source

» Darwin noted that since some of these species without enough food survived then there must be something special about them, which helps them to survive

Natural SelectionNatural Selection

• 1858 20 years after his voyage on the HMS Beagle Darwin received a letter from Alfred Russel Wallace

had independently come up with the same theory of evolution that Darwin had been working on

• Published “On the Origins of Species by Natural Selection” • Theory evolution occurs through a process called natural

selection

Natural SelectionNatural Selection

More evidence of evolutionMore evidence of evolution

• Evolution by natural selection parents pass traits to their offspring

• 1930-40 biologists combined principles of genetic inheritance and Darwin’s theory of evolution by natural selection

• Mutations responsible for the changes Darwin saw (changes at the

DNA level)

The Evolution of Living The Evolution of Living ThingsThings

Chapter 8.3 Natural Selection in ActionChapter 8.3 Natural Selection in Action

Natural selection in actionNatural selection in action

• The Theory of Natural Selection how populations change over many generations to adapt to changes in the environment

Insecticide ResistanceInsecticide Resistance

• Resistance to insecticides over 500 species of insects have developed a resistance to

certain insecticides• Quick adaptation they evolve quickly to resist certain

poisons quickly because they have short generation times

• Generation time the period between the birth of one generation to the birth of another

generation• Antibiotic resistant disease tuberculosis and other diseases are

becoming resistant to antibiotics because the surviving microorganisms are becoming strong antibiotic-resistant strains

Adaptation to pollutionAdaptation to pollution

• Example European peppered moth

Originally dark moths were easier for birds to see and eat, after the influence of pollution turned nearby tree trunks darker the lighter moths were easier to see and eat for the birdsMore dark moths survived and produced offspring that were dark, so the population shifted.

Formation of a new speciesFormation of a new species

• Process of natural selection explains how a species can evolve into a new species

• 1-Separation a portion of the population is cut off from the rest of the population

• 2-Adaptation separated groups may adapt to fit their environment

• 3-Division oven hundreds, thousands, or even millions of years the two groups may become so different that they can’t interbreed

– When species can’t interbreed they are no longer considered to be the same species